I have just replaced a Quick brand hotter heater with a different brand heater. I can't remember the brand name but it comes from the US of A.

I have had the old heater removed for a few weeks now and I had continued to use the boat/engine by just looping back one of the coolant hoses that ran through the heater tank back into the engine. I have forgotten which hose was ran where. Does it matter to the heater how the coolant runs iie. coolant in and coolant out, and how it runs into and out of the engine, or does it not matter as long as there is a completed circuit?

Cheers.